The present invention refers to a module for supporting a wound foil for a machine processing, the foil, and more particularly for a machine using stamping foils for manufacturing packaging.
Such a machine is used for the embossing and the transfer by pressure of film portions, preferably of metal, coming from such foils onto a substrate of paper, plastic material or more particularly cardboard. These operations are for example carried out in a machine equipped with a platen press which processes plate-like elements, such as sheets of cardboard, for the foil stamping of given patterns. These patterns come from a stamping foil led between the travelling plane of the plate-like elements and the upper beam of the press. In intermittent vertical movements, the movable lower platen presses the stamping foil against each cardboard sheet between printing plates and corresponding counterparts in order to deposit the metallic layer of the stamping foil in correspondence with the patterns of the printing plates. Once the transfer has been carried out, the lower platen lowers and the stamped cardboard sheet is withdrawn from the platen press leaving the space for a new sheet. During the same period of time, the stamping foil is moved so that a new blank sheet is placed in correspondence with the printing plates. The diecutting and transfer operation of the foil can then be repeated.
Such a machine can also be used for the diecutting of cardboard sheets in a succession of operations each carried out in an adjacent station. This succession of operations generally comprises the infeed of the sheet into the press, its diecutting by tools arranged on the platen, the stripping of waste by specific tools and the delivery in stacks of the diecut sheet elements. In order to optimize the possibilities of such a machine, it is known to convert it so that the initial diecutting station becomes a stamping station for stamping foils by replacing the diecutting tools by a stamping device and the tools of the stripping station by a device for loading and unwinding stamping foil reels. Such a conversion is illustrated by the machine described in patent EP 741'096.
The arrangement of a foil loading and unwinding device in the stripping station within such a machine is described in detail in patent EP 741'096. This device in particular comprises a pair of parallel vertical arms between which crossbars are arranged to be used as supports for a plurality of stamping foil reels. The foil widths are typically of the order of 5 to 20 cm. It should be noted that these stamping foils carrying patterns, or foils called diffraction foils, are generally realized by depositing, through printing, a decorative metallic layer on a substrate consisting of a flexible material, for example plastic material. Because of the way in which they are made, these stamping foils include a fine connecting line issuing from the cylindrical printing plate carrying the pattern to print which, obviously, cannot cover the 360° of the plate cylinder. Therefore, this fine connecting line will appear at each revolution of the plate cylinder and it should be prevented that this connecting line comes in conflict with one of the patterns to stamp.
Due to the transverse arrangement of the rotation axes of the reels with respect to the longitudinal axis of the machine, the unwinding of the foils takes place parallel to the travelling direction of the sheets to stamp. The transport of these foils requires intermittent unwinding and advancing means generally comprised of rollers against which the foils are seized by pressure rollers. The motorized drive of these rollers allows intermittent feed of these foils. According to the desired speed profiles of the respective foils, it is possible to provide a plurality of advancing rollers so that each foil can be independently driven. When using wider foils, it is necessary to provide a plurality of pressure rollers per foil. These pressure rollers are mounted in a slidable manner on transverse axes, so that they can be positioned in completely independent manner. However, the whole apparatus formed by the reel loading and supporting device, the idling rollers, the drive rollers, their motorization as well as the pressure rollers adjustable in position, requires related operations when such a device is to be mounted within a diecutting machine for its conversion into a stamping machine. Since these conversion operations cannot be performed when the machine is running, they immobilize the machine for hours and contribute to an increase in price of the future production, mainly for production of small series.
Although the majority of the metallic layers deposited on the packaging can be supplied from narrow foils, generally not exceeding 30 cm, sometimes wider stamping foils have to be used, typically of the order of 50 to 70 cm, or a plurality of narrow foils arranged side by side have to be used, the total width of which approaches this magnitude.
However, the use of wide reels raises handling problems. Because of their weight, it is obviously impossible to move these reels with the physical strength of one man for positioning them in the machine. Thus, lifting means should be used, such as hoists or small vehicles able to easily move heavy loads. However, the positioning of such reels by these means makes the handling them in a machine delicate, and sometimes even impossible, either because of lack of space around the machine, or due to the impossibility of access inside the machine which was not intended for receiving such means.